The objective is to develop a non-invasive, reliable, safe, and rapid system for measuring body volume in humans and animals. There is a critical biomedical need for body volume and compostion determination for infants and children. A volume measurement technique which requires little subject cooperation, unlike currently available methods, could be usefully applied to neonates, children, adults, and animals. The Acoustic Body Volumeter (ABV) is an innovative system which will meet these criteria. In Phase I, the application of the ABV was extended from small volumes in anechoic spaces to larger volumes in non-anechoic spaces. Phase II objectives are to: 1) test the accuracy of the ABV in measuring humans, relative to commonly used methods, 2) further extend our understanding of effects of parameters including subject position, motion, hair, clothing and respiration, 3) automate the ABV operation, and 4) determine the specific needs of potential users of the ABV. In Phase III, the ABV will be manufactured and marketed. An ABV will be extremely useful to several groups: clinics and research laboratories studying nutrition and body development, agricultural companies studying animal nutrition, sports organizations interested in athletes' body composition, and weight control centers monitoring changes in body composition.